Six German states have told retailers to stop selling Red Bull cola drinks after a test found traces of cocaine. The bans came into force on Friday after a sample test by officials in North Rhine-Westphalia found 0.4 micrograms a litre. Five other states also issued a ban amid concerns over possible drug law violations. Germany's federal institute for risk assessment said yesterday that the cocaine level was too low to pose a health risk. It planned to produce a more detailed report tomorrow. Red Bull said its cola was "harmless" and that a test it commissioned found no cocaine traces.